<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="./vue.js"></script>
</head>

<body>
  <div id="app">

    <div v-for="(val,key,index) in user" :key="index">
      {{val}}-{{key}}-{{index}}
    </div>
    <hr>
    <ul>
      <li v-for="c in cities">{{c}}</li>
    </ul>

  </div>
  <script>

    var vm = new Vue({
      el: "#app",
      data: {
        cities: ['北京', '太原'],
        user: {
          name: "duanpeng",
          age: 18,
          address: 'taiyuan'
        }
      },
      mounted() {
        setTimeout(() => {
          this.cities.splice(0, 1, '天津')
        }, 2000)
      }

    })
  </script>
</body>

</html>